Google PageSpeed Insights measures how fast your web pages load and provides a score from 0–100. Images are the single biggest opportunity for improvement on most websites — often responsible for 60–80% of page weight. Here is how to optimise images to pass Google's tests.
Google PageSpeed Image Requirements
- Serve images in next-gen formats: Use WebP or AVIF instead of JPG and PNG
- Properly size images: Do not serve 2000px images in 400px containers
- Efficiently encode images: Compress images appropriately for their display size
- Defer offscreen images: Use lazy loading for images below the fold
Step-by-Step PageSpeed Image Optimisation
- Run Google PageSpeed Insights on your URL — note all image-related warnings
- Identify each flagged image and its display dimensions on the page
- Resize each image in imgresizr.com to the display dimensions (no larger)
- Convert JPG and PNG images to WebP format using imgresizr.com's convert tool
- Compress the WebP to 80–85% quality for optimal size/quality balance
- Replace old images with optimised versions on your website
- Add lazy loading attribute to all images below the fold: loading="lazy"
- Re-run PageSpeed and verify improvement
Expected PageSpeed Improvements
| Optimisation | Typical Improvement |
|---|---|
| Resize oversized images | 30–60% reduction in image bytes |
| Convert to WebP | Additional 25–35% reduction |
| Apply compression | Additional 20–40% reduction |
Optimise all your images for Google PageSpeed at imgresizr.com — resize, convert to WebP, and compress for free.